Recently, a research on a plant biotechnology which breeds useful plants by taking out various cells and tissue organs which constitute individual plants, and performing various artificial operations such as cell fusion, mutagen processing, gene manipulation, etc,, and reproducing individual plants has drawn attention.
For example, a method of breeding seedlings by using shoot apex culture, whose basic concept is shown in FIG. 26, includes a stage of bedding and multiplying on an agar culture medium within a container plant tissues cut from a predetermined portion of a plant, a germinating stage of transplanting the multiplied plant tissues into another container and causing them to germinate therein, a root-making stage of dividing, cutting and transporting causing the germinated plant portions into another container and causing to make root, and an acclimating stage of taking the plant portions which have made out of the container, washing them in an agar, humidifying them in a light-screened state within an acclimating device to cause the washed plant portions to make root again and to acclimate them to the ambience. After acclimation, they are transplanted into a pot for breeding purposes. In the respective multiplying, germinating and root-making stages, they are cultured using the agar culture medium which contains the respective optimal ingredients, and transplantation is required to be made at least once in each of the culturing stages, which requires significant labor and cost problematically.
It is desirable to exchange culture medium components and to feed gas in each stage in order to optimize the gas and the culture medium components at all times. However, gas is difficult to feed and discharge gas within a test tube. Transplantation is necessarily required to exchange the culture medium components in the agar culture medium, so that the components conditions are selected substantially once at most at each of the stages in view of working efficiency and damage to living plants. Therefore, especially, there are many cases in which roots made at the root-making stage insufficiently extends due to failure of oxygen to thereby become malformed.
When young plants which have made root are moved to the acclimating stage, they are moved to a planting nutrient medium such as vermiculite. At this time, washing is required to prevent the contamination with mold and bacteria because the agar culture medium used at the root-making stage contains sugar. This washing requires significant labor, can easily damage the roots and retard the growth of the young plants.
The inventors proposed a device which implants cultured tissues such as adventive buds or adventive embryos into a nutrient medium support impregnated with a nutrient medium solution disposed within a hermetically sealded container, feeds and discharges a nutrient medium solution to and from the nutrient medium support, and feeds and discharges the gas component to and from the container to optimize at all times the nutrient solution and gas necessary for culturing them to thereby cause the cultured tissues to make root and to acclimate to the ambient conditions (Specifications of Japanese Patent Applications Nos. 61-187691 and 61-187692).
According to this device, no transplantation is required and the gas and nutrient medium components are maintained in an optimal state, so that cultured tissues are grown well with high working efficiency. Also, in acclimation no transplantation is required and the cultured tissues are acclimated under good conditions without stopping the growth of the roots. Therefore, inexpensive and high-speed growth results--excellent effects.
However, tissue culture is very likely to be damaged by entering mold or bacteria. Therefore, handling must be performed on a clean bench. In additon, a skillful operator is required. It is difficult to adjust the nutrient medium solution, to feed and discharge gas many times while preventing the invasion of mold or bacteria, which is one cause to prevent the practical use of the tissue culture.
In order to multiply individual plants by tissue culture, shoot apexes and axillary buds are used from a standpoint of virus free.
Conventionally, one of the tissue culture methods using shoot apexes and axillary buds includes changing plant tissues, cut from the shoot apexes or axillary buds, to calluses in an agar culture medium containing plant growth regulator, for example, 2.4-D, etc., multiplying the calluses in the liquid nutrient medium, and passing the multiplied calluses through a sieve including a first filter of a 100 .mu.m-screen and a second filter of a 50 .mu.m-screen.
Thereafter, small cellar masses of a uniform size (50 .mu.m&lt;.times.&lt;100 .mu.m) remaining on the second filter are washed away in a liquid nutrient medium which contains 2.4-D free medium and then washed better and changed to adventive embryos in a new nutrient medium.
The resulting products are then filtered to obtain uniform-sized adventive embryos.
Thereafter, they are classified according to shape and color and bedded to the nutrient medium.
Such a work is done almost manually. In order to avoid contamination by various germs the work must be done on a clean bench, which requires careful and skilled techniques.
Especially in bedding, many adventive embryos cultured, for example in a tank, are planted manually one by one, so that the bedding process is a factor of hindering batch processing in the course of the entire operation.
In view of the above situation, the present invention has been made. It is an object of the present invention to provide a young plant breeding apparatus which prevents mold or bacteria from entering the apparatus and breeds the young plants inexpensively at high speeds.
In view of the above situation, the present invention has been made. It is an object of the present invention to facilitate the selection and bedding of cultured tissues, to sterilize cultured tissues and to improve the efficiency of the tissue culture.